glibc/sysdeps/loongarch/dl-machine.h

/* Machine-dependent ELF dynamic relocation inline functions.
   Copyright (C) 2022 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library.  If not, see
   <https://www.gnu.org/licenses/>.  */

#ifndef dl_machine_h
#define dl_machine_h

#define ELF_MACHINE_NAME "LoongArch"

#include <entry.h>
#include <elf/elf.h>
#include <sys/asm.h>
#include <dl-tls.h>
#include <dl-static-tls.h>
#include <dl-machine-rel.h>

#ifndef _RTLD_PROLOGUE
# define _RTLD_PROLOGUE(entry)					\
	".globl\t" __STRING (entry) "\n\t"			\
	".type\t" __STRING (entry) ", @function\n\t"		\
	CFI_STARTPROC "\n"					\
	__STRING (entry) ":\n"
#endif

#ifndef _RTLD_EPILOGUE
# define _RTLD_EPILOGUE(entry)					\
	CFI_ENDPROC "\n\t"					\
	".size\t" __STRING (entry) ", . - " __STRING (entry) "\n"
#endif

#define ELF_MACHINE_JMP_SLOT R_LARCH_JUMP_SLOT
#define ELF_MACHINE_IRELATIVE R_LARCH_IRELATIVE

#define elf_machine_type_class(type)				\
  ((ELF_RTYPE_CLASS_PLT *((type) == ELF_MACHINE_JMP_SLOT))	\
   | (ELF_RTYPE_CLASS_COPY *((type) == R_LARCH_COPY)))

#define ELF_MACHINE_NO_REL 1
#define ELF_MACHINE_NO_RELA 0

/* Return nonzero iff ELF header is compatible with the running host.  */
static inline int
elf_machine_matches_host (const ElfW (Ehdr) *ehdr)
{
  /* We can only run LoongArch binaries.  */
  if (ehdr->e_machine != EM_LOONGARCH)
    return 0;

  return 1;
}

/* Return the run-time load address of the shared object.  */
static inline ElfW (Addr) elf_machine_load_address (void)
{
  extern const ElfW(Ehdr) __ehdr_start attribute_hidden;
  return (ElfW(Addr)) &__ehdr_start;
}

/* Return the link-time address of _DYNAMIC.  */
static inline ElfW (Addr) elf_machine_dynamic (void)
{
  extern ElfW(Dyn) _DYNAMIC[] attribute_hidden;
  return (ElfW(Addr)) _DYNAMIC - elf_machine_load_address ();
}

/* Initial entry point code for the dynamic linker.
   The C function `_dl_start' is the real entry point;
   its return value is the user program's entry point.  */

#define RTLD_START asm (\
	".text\n\
	" _RTLD_PROLOGUE (ENTRY_POINT) "\
	.cfi_label .Ldummy   \n\
	" CFI_UNDEFINED (1) "   \n\
	or	$a0, $sp, $zero   \n\
	bl	_dl_start   \n\
	# Stash user entry point in s0.   \n\
	or	$s0, $v0, $zero   \n\
	# Load the original argument count.   \n\
	ld.d	$a1, $sp, 0   \n\
	# Call _dl_init (struct link_map *main_map, int argc, \
			 char **argv, char **env)    \n\
	la	$a0, _rtld_local   \n\
	ld.d	$a0, $a0, 0   \n\
	addi.d	$a2, $sp, 8   \n\
	slli.d	$a3, $a1, 3   \n\
	add.d	$a3, $a3, $a2   \n\
	addi.d	$a3, $a3, 8   \n\
	# Stash the stack pointer in s1.\n\
	or	$s1, $sp, $zero	\n\
	# Adjust $sp for 16-aligned   \n\
	bstrins.d	$sp, $zero, 3, 0  \n\
	# Call the function to run the initializers.   \n\
	bl	_dl_init   \n\
	# Restore the stack pointer for _start.\n\
	or	$sp, $s1, $zero	 \n\
	# Pass our finalizer function to _start.   \n\
	la	$a0, _dl_fini   \n\
	# Jump to the user entry point.   \n\
	jirl	$zero, $s0, 0   \n\
	" _RTLD_EPILOGUE (ENTRY_POINT) "\
	.previous");

/* Names of the architecture-specific auditing callback functions.  */
#define ARCH_LA_PLTENTER loongarch_gnu_pltenter
#define ARCH_LA_PLTEXIT loongarch_gnu_pltexit

/* Bias .got.plt entry by the offset requested by the PLT header.  */
#define elf_machine_plt_value(map, reloc, value) (value)

static inline ElfW (Addr)
elf_machine_fixup_plt (struct link_map *map, lookup_t t,
			 const ElfW (Sym) *refsym, const ElfW (Sym) *sym,
			 const ElfW (Rela) *reloc, ElfW (Addr) *reloc_addr,
			 ElfW (Addr) value)
{
  return *reloc_addr = value;
}

#endif /* !dl_machine_h */

#ifdef RESOLVE_MAP

/* Perform a relocation described by R_INFO at the location pointed to
   by RELOC_ADDR.  SYM is the relocation symbol specified by R_INFO and
   MAP is the object containing the reloc.  */

static inline void __attribute__ ((always_inline))
elf_machine_rela (struct link_map *map, struct r_scope_elem *scope[],
		  const ElfW (Rela) *reloc,
		  const ElfW (Sym) *sym,
		  const struct r_found_version *version,
		  void *const reloc_addr, int skip_ifunc)
{
  ElfW (Addr) r_info = reloc->r_info;
  const unsigned long int r_type = ELFW (R_TYPE) (r_info);
  ElfW (Addr) *addr_field = (ElfW (Addr) *) reloc_addr;
  const ElfW (Sym) *const __attribute__ ((unused)) refsym = sym;
  struct link_map *sym_map = RESOLVE_MAP (map, scope, &sym, version, r_type);
  ElfW (Addr) value = 0;
  if (sym_map != NULL)
    value = SYMBOL_ADDRESS (sym_map, sym, true) + reloc->r_addend;

  if (sym != NULL
      && __glibc_unlikely (ELFW (ST_TYPE) (sym->st_info) == STT_GNU_IFUNC)
      && __glibc_likely (sym->st_shndx != SHN_UNDEF)
      && __glibc_likely (!skip_ifunc))
    value = ((ElfW (Addr) (*) (int)) value) (GLRO (dl_hwcap));

  switch (r_type)
    {

    case R_LARCH_JUMP_SLOT:
    case __WORDSIZE == 64 ? R_LARCH_64 : R_LARCH_32:
      *addr_field = value;
      break;

    case R_LARCH_NONE:
      break;

#ifndef RTLD_BOOTSTRAP
    case __WORDSIZE == 64 ? R_LARCH_TLS_DTPMOD64 : R_LARCH_TLS_DTPMOD32:
      *addr_field = sym_map->l_tls_modid;
      break;

    case __WORDSIZE == 64 ? R_LARCH_TLS_DTPREL64 : R_LARCH_TLS_DTPREL32:
      *addr_field = TLS_DTPREL_VALUE (sym) + reloc->r_addend;
      break;

    case __WORDSIZE == 64 ? R_LARCH_TLS_TPREL64 : R_LARCH_TLS_TPREL32:
      CHECK_STATIC_TLS (map, sym_map);
      *addr_field = TLS_TPREL_VALUE (sym_map, sym) + reloc->r_addend;
      break;

    case R_LARCH_COPY:
      {
	  if (sym == NULL)
	    /* This can happen in trace mode if an object could not be
	       found.  */
	    break;
	  if (__glibc_unlikely (sym->st_size > refsym->st_size)
	      || (__glibc_unlikely (sym->st_size < refsym->st_size)
		&& GLRO(dl_verbose)))
	  {
	    const char *strtab;

	    strtab = (const char *) D_PTR (map, l_info[DT_STRTAB]);
	    _dl_error_printf ("\
%s: Symbol `%s' has different size in shared object, consider re-linking\n",
	    rtld_progname ?: "<program name unknown>",
	    strtab + refsym->st_name);
	  }
	  memcpy (reloc_addr, (void *) value,
		  MIN (sym->st_size, refsym->st_size));
	    break;
      }

    case R_LARCH_RELATIVE:
      *addr_field = map->l_addr + reloc->r_addend;
      break;

    case R_LARCH_IRELATIVE:
      value = map->l_addr + reloc->r_addend;
      if (__glibc_likely (!skip_ifunc))
	value = ((ElfW (Addr) (*) (void)) value) ();
      *addr_field = value;
      break;

#endif

    default:
      _dl_reloc_bad_type (map, r_type, 0);
      break;
    }
}

static inline void __attribute__ ((always_inline))
elf_machine_rela_relative (ElfW (Addr) l_addr, const ElfW (Rela) *reloc,
			   void *const reloc_addr)
{
  *(ElfW (Addr) *) reloc_addr = l_addr + reloc->r_addend;
}

static inline void __attribute__ ((always_inline))
elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
		      ElfW (Addr) l_addr,
		      const ElfW (Rela) *reloc, int skip_ifunc)
{
  ElfW (Addr) *const reloc_addr = (void *) (l_addr + reloc->r_offset);
  const unsigned int r_type = ELFW (R_TYPE) (reloc->r_info);

  /* Check for unexpected PLT reloc type.  */
  if (__glibc_likely (r_type == R_LARCH_JUMP_SLOT))
    {
      if (__glibc_unlikely (map->l_mach.plt == 0))
	{
	  if (l_addr)
	    *reloc_addr += l_addr;
	}
      else
	*reloc_addr = map->l_mach.plt;
    }
  else
    _dl_reloc_bad_type (map, r_type, 1);
}

/* Set up the loaded object described by L so its stub function
   will jump to the on-demand fixup code __dl_runtime_resolve.  */

static inline int __attribute__ ((always_inline))
elf_machine_runtime_setup (struct link_map *l, struct r_scope_elem *scope[],
			   int lazy, int profile)
{
#ifndef RTLD_BOOTSTRAP
  /* If using PLTs, fill in the first two entries of .got.plt.  */
  if (l->l_info[DT_JMPREL])
    {
      extern void _dl_runtime_resolve (void)
	__attribute__ ((visibility ("hidden")));
      ElfW (Addr) *gotplt = (ElfW (Addr) *) D_PTR (l, l_info[DT_PLTGOT]);
      gotplt[0] = (ElfW (Addr)) & _dl_runtime_resolve;
      gotplt[1] = (ElfW (Addr)) l;
    }
#endif

  return lazy;
}

#endif /* RESOLVE_MAP */